1. Technical Field
The present invention relates to printing methods, storage media, media, printing apparatuses, methods for detecting an end of an image, methods for detecting carrying unevenness of a medium, and devices for detecting carrying unevenness of a medium.
2. Related Art
(1) Inkjet printers (hereinafter, referred to as “printers”) are known as printing apparatuses for forming an image by ejecting ink onto paper serving as a medium. These printers repeat in alternation a dot forming operation in which dots are formed on paper by ejecting ink from a plurality of nozzles moving in a movement direction of a carriage, and a carrying operation in which a carry unit carries the paper in an intersecting direction (hereinafter, also referred to as “carrying direction”) that intersects the movement direction. Thus, a plurality of raster lines constituted by a plurality of dots along the movement direction are formed in the intersecting direction, so that an image is printed (see JP-A-06-166247).
However, in the printers as above, there is a possibility that an image is printed at an angle with respect to paper due to, for example, the characteristics of a paper carry mechanism of the printers. Furthermore, in the printers as above, there is a case in which a predetermined pattern used for adjusting the printers and other purposes is printed in addition to an ordinary image such as letters and sceneries. There is a problem that it may be impossible to perform adjustment well when such a predetermined pattern used for adjustment and other purposes is printed at an angle with respect to paper, and adjustment is performed without noticing that the pattern is at an angle.
(2) Furthermore, there is a case in which it is required to detect the area of an image, that is, an end portion of the image by reading the image that has been printed in the printing apparatuses as above with a reading device and the like.
However, in the printers as above, ink may spread over the area that is to be printed originally at an end portion of the image, for example, because the ink that has been ejected on the paper smudges. Thus, there is a possibility that the area of the printed image is larger than the area of the image that is to be printed originally, so that it is impossible to accurately detect the end portion of the image.
(3) Furthermore, in printing apparatuses such as inkjet printers, a process is performed in which ejection non-uniformity of ink is adjusted by reading the darkness of a test pattern that has been printed by the printing apparatuses (see JP-A-H02-54676). In this process, the darkness of the printed test pattern is read by a darkness reading device such as a scanner, for example.
There is a case in which when a test pattern is printed, paper is carried askew, for example, because the paper slips on a paper sending roller or the paper is excessively pressed by a paper guide. For example, there is a case in which paper is carried in a curve because the carrying amount is uneven between one side and the other side in the width direction of the paper (hereinafter, the phenomenon in which paper is carried in a curve is also referred to as “skew”). When the skew occurs, the test pattern is printed in a deformed state, and thus the accuracy in adjustment is degraded. However, it is difficult to detect this skew by visual observation.